Pernicious Anaemia (PA) and Associated Conditions

People with Pernicious Anaemia (PA), an autoimmune condition, have a significantly higher risk of developing other autoimmune diseases and related comorbidities. Patient surveys indicate that nearly half of individuals with PA report one or more additional autoimmune diagnoses, with strong familial clustering also observed.

The reasons for this clustering are not fully understood but are believed to involve shared genetic and immunological factors. Ongoing research, including studies supported by the Pernicious Anaemia Society in collaboration with initiatives like the James Lind Alliance Priority Setting Partnership, is investigating potential common genetic links that may explain the predisposition to multiple autoimmune conditions.
Below is an overview of commonly associated conditions based on patient reports and clinical associations. This list is not exhaustive, and individual experiences vary. 

Approximately 67% reported other non-AID comorbidities, including asthma (30%), depression (27%), arrhythmia (11%), and type 2 diabetes (6%).

Additionally, 60% reported at least one other micronutrient deficiency at diagnosis (beyond B12), most commonly iron (40%), vitamin D (27%), and folate (24%).

1. Autoimmune Thyroid Disease (e.g., Hashimoto’s Thyroiditis or Graves’ Disease)

These conditions involve an overactive or underactive thyroid and frequently co-occur with PA. Symptoms overlap with PA, such as fatigue, cognitive issues, and weight changes. Diagnosis involves thyroid function tests and antibody screening; treatment uses hormone replacement or suppression as appropriate. This is one of the most common comorbidities.
Patients with Autoimmune Thyroid Disease (AITD) have a high prevalence of B12 deficiency and particularly of Pernicious Anaemia. Up to 28% of patients with AITD have low B12 levels.

2. Vitiligo

Vitiligo causes loss of skin pigment, resulting in irregular pale or white patches. It is considered autoimmune with genetic components and is chronic. Treatments may include cosmetic camouflage, topical steroids, calcineurin inhibitors, or UV light therapy.

3. Diabetes

Type 1 diabetes is an autoimmune condition where blood glucose levels are too high because the pancreas cannot produce insulin, and this insulin needs to be replaced either by injections or an insulin pump.

4. Rheumatoid Arthritis

Where the body’s auto-immune system attacks the bone joints leading to what can be a severely painful condition that makes moving of certain parts of the body very difficult. There are various treatments used to treat RA including Cortisone therapy.

5. Psoriasis

Psoriasis involves accelerated skin cell turnover, leading to red, scaly patches. It can be chronic or involve flare-ups (sometimes seasonally). Treatments include topical steroid creams, vitamin D analogues, phototherapy (UV light), and systemic medications for more severe cases. Effectiveness varies by individual.
Psoriatic Arthritis
This inflammatory arthritis often develops in people with psoriasis (typically years later) and causes joint pain, stiffness, and swelling, particularly in the fingers and toes (dactylitis). Management typically involves anti-inflammatory drugs, disease-modifying antirheumatic drugs (DMARDs), or biologics.

6. Tinnitus

Many individuals with PA experience tinnitus, often described as ringing, whistling, howling, or other noises in one or both ears. These sounds may be intermittent or persistent and can range from mild to highly disruptive. While the exact link is not fully elucidated, it may relate to neurological effects of B12 deficiency.

7. Coeliac Disease

This autoimmune reaction to gluten damages the small intestine, leading to malabsorption (which can compound B12 issues) and symptoms like diarrhoea. Strict lifelong gluten-free diet is the primary treatment.

8. Rosacea

Rosacea primarily affects fair-skinned individuals of Northern European descent and presents with facial redness, visible blood vessels, and sometimes pustules. Treatments often include topical or oral antibiotics, anti-inflammatory agents, or laser therapy, depending on the subtype.

9. Eczema (Atopic Dermatitis)

Eczema encompasses various inflammatory skin conditions ranging from mild itching to widespread red, inflamed skin. Triggers vary; treatments include moisturisers, topical steroids, and other immunomodulators.

Patient data from the PAS highlights other frequent associations. Many members also report non-autoimmune comorbidities. Family history of autoimmune diseases is common,

Reference:
Thain A, et al. Patient-reported characteristics of pernicious anaemia: a first step to initiate James Lind Alliance Priority Setting Partnership driven research. BMC Primary Care. 2025. https://bmcprimcare.biomedcentral.com/articles/10.1186/s12875-025-03036-0